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  #1  
Old 24-10-2008, 12:49 PM
3wheelsgood 3wheelsgood is offline
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Default Swing arm help

Hi Guys,

I'm toying with the idea of chopping either a Honda VTX or a Suzuki Intruder and my plans would mean me either having to extend the length of the swing arm or move the pivot point further back.
As both these bikes are shaft drive I can see some potential problems.

A. Cutting and extending the shaft would cause vibration if the shaft is not perfectly balanced again.
B. Having a longer swing arm may mean the shaft would move up and down through a longer arc, possibly fouling the gearbox.

Does anyone have any experience of extending a shaft drive and what problems I might run into? or should I try to base my plans on something chain driven?
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  #2  
Old 24-10-2008, 08:06 PM
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TektroG TektroG is offline
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Pretty sure chain would be more straightforward, but Blackjack is the man you need.

Shouldn't this be in the workshop mods?
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  #3  
Old 25-10-2008, 04:04 AM
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dracken1 dracken1 is offline
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this is how thunderbike get over the vs1400 issue

Last edited by dracken1; 25-10-2008 at 04:06 AM.
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Old 25-10-2008, 08:09 AM
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Thers a couple of ways of extending a shaft either with a spacer plate/extention at the UJ or my prefered method of cutting the shaft

I cut the shaft a few inches from one end & have an extension piece made up that the cut end of the shaft will press into by 2" (interfearance fit) either end & with the required extra length in the middle i then weld this & dress the welds, no problems so far with balance so far with up to 6" of extension

hope it makes sense & helps
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Old 25-10-2008, 08:13 AM
3wheelsgood 3wheelsgood is offline
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Thanks for the picture Draken.

I'm trying to work out what he's done there - seems to be a UJ cut into the shaft?

I'd be grateful for anybody elses advise or opinions.

Sorry if I posted this in the wrong place - I'm new here! be gentle with me.
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  #6  
Old 25-10-2008, 10:11 AM
3wheelsgood 3wheelsgood is offline
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Thanks Slim.

That makes perfect sense. It doesn't sound as difficult as I first expected.
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  #7  
Old 25-10-2008, 10:33 AM
Blackjack Blackjack is offline
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The important thing about the converion kit is that it runes a support bearing for the shaft.

You can't have more than 2 UJ's in an unsupported shaft or it has a tendency to tie itself in knots.

Extending the shaft isn't stupidly hard, the small diameter of it means that balance is less of an issue because the out of balance centre of mass is so close to the centre line of the shaft. Think of putting a weight on a record player turn table, the further from the middle you put it, the sooner it flies off.

Moving the pivot is a bit fraught, it needs to be in line with the front UJ. Conflicting arcs and the lack of a plunge joint are going to destroy something otherwise.

If you saw the article where I stretched the Z550 swing arm, it's basically the same approach for a shaft drive, but you build the fixture for the rear end of the arm and move the front end along the jig making sure it stays on a line perpendicualr to the centre of the mounting flange for the bevel box.

Off the top of my head, I'd replace the side of the swing arm that has the spindle mount with a new piece of tube/box, and have a look at getting another arm and sleeing two originals together on the bevel side.

If I was actually looking at one, I might change my mind about that though.

Last edited by Blackjack; 25-10-2008 at 10:34 AM. Reason: Just woke up and don't appear to be able to spiel.
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Old 25-10-2008, 03:09 PM
3wheelsgood 3wheelsgood is offline
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Thank you Blackjack - some really useful information there, and the job doesn't seem so daunting as it did - although I guess that if I stick to a chain drive I can avoid all these issues. However, finding a large V-twin with a chain drive is another issue.

I would be interested in seeing your article about the Z550 swing arm, do you know where I can find it?
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  #9  
Old 25-10-2008, 09:00 PM
Blackjack Blackjack is offline
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Shed Head in 100% Biker.

Got no idea which issue, and I'm on my laptop and I don't have all my files on it.

Unless someone else knows, it'll be Monday evening before I can have a look, and then it depends on whether it was before I started namng files by issue number or not...
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